赤道印度洋海温异常与偶极子季节变化特征

利用Scripps海温再分析资料,对赤道印度洋0～400m深度范围内海温变化和偶极子异常变化特征进行了初步分析。结果显示,赤道印度洋上层海温呈现西低东高,而次表层以下海温则为西高东低。同时发现,温跃层是赤道印度洋上、下层很好的分界面。温跃层之上海温变化受海气相互作用明显,之下海温变化主要受海洋自身的运动影响。赤道印度洋偶极子现象存在于各个深度,其偶极子指数变化存在半年周期,季节变化表现为双峰双谷型,并从深层（400m）向表层传递。分析发现,海气相互作用不是表层赤道印度洋偶极子变化的决定因素。较深层偶极子变化决定于海洋自身的运动变化特征（如洋流）,并向上层传输,进而影响上层偶极子的异常变化。赤道印度洋偶极子指数由西印度洋和东印度洋海温变化共同制约,但西印度洋海温变化起主导作用,东印度洋仅起到加强或减弱偶极子强度变化的作用。

SEASONAL VARIATION IN THE SEA TEMPERATURE AND DIPOLE IN THE TROPICAL INDIAN OCEAN

In this paper,we used sea temperature from reanalysis data of Scripps JEDAC to study the seasonal variation in sea temperature between 0-400 meters of the tropical Indian Ocean and anomalies of the Indian Ocean dipole.The temperature in the upper layer of tropical Indian Ocean is higher in the east and lower in the west,while it is reverse in the deeper layer.The thermocline is a good interface between the upper level and the low level in the tropical Indian Ocean.In the upper layer,there is obvious sea-atmosphere interaction,while below it the sea temperature is mainly affected by ocean's movement.The Indian Ocean dipole exists in all levels from surface to 400m.The Dipole Mode Index(DMI)has a period of half-year,turning to be a two-peak-two-trough pattern over a year.The peaks and troughs transfer from 400 meters level to the surface in two months.The dipole mode change of surface in the tropical Indian Ocean is not only determined by air-sea interaction.Ocean's movement,such as ocean current,determines the deep level dipole,and its upward transfer affects the dipole in the upper layer,thereby.The sea temperature in western and eastern parts co-affects the DMI in the tropical Indian Ocean,with western sea temperature as a leading factor,and eastern temperature as a secondary factor.